The question everyone is asking about the royal family's Father's Day tribute.

For much of the world, Sunday was Father’s Day. And so in true 2017 fashion, many celebrated the occasion by posting a great photo online.

Even the British Royal Family got involved, with the official Kensington Palace Twitter account posting a throwback image of Prince Charles with William and Harry, and Wills cuddling young Prince George.

Happy Father’s Day. Wishing all the fathers out there a very happy day pic.twitter.com/Lgm0ZnOCMT

— Kensington Palace (@KensingtonRoyal) June 18, 2017

There’s no denying they’re cute snaps. And yes, bowl cuts will never not be adorable.

But people on social media can’t help but notice there’s someone very important missing from the post, which honours the special relationships between royal fathers and their children.

Where, oh where, is Princess Charlotte?

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The toddler’s notable absence has left many Royal fans scratching their heads.

“Odd there’s only picture (sic) with his son? Where’s his daughter?’, one comment read.

Another wrote, “Where’s Charlotte? Isn’t William also a dad to Charlotte or do only boys matter?”

Odd there’s only picture with his son? Where’s his daughter?

— Lilly (@lillype) June 18, 2017

Where’s Charlotte? Isn’t William also a dad to Charlotte or do only boys matter?

— ElsaMuse (@ElsaMusePinUp) June 18, 2017

The tribute is seemingly innocent, but it does raise the question of just how modern the new era of the British monarchy really is.

Prince Charles’ female sibling, Princess Anne was also missing from a similar post shared by The Prince of Wales and The Duchess of Cornwall’s official Twitter account, which shared a picture of Charles with father, The Duke of Edinburgh.

Happy #FathersDay!

The Prince of Wales and his father, The Duke of Edinburgh, take part in a motorboat race on the Isle of Wight in 1958. pic.twitter.com/DHd7EfkEss

— Clarence House (@ClarenceHouse) June 18, 2017

Although it appears to be royal protocol to only acknowledge past, present and future dads on Father’s Day, perhaps it’s time Kensington Palace widened the tradition to be more inclusive? Fans on social media certainly think so.